Synthesis, structure and photophysical properties of [UO2X2(O=PPh3)2] (X = Cl, Br, I)

The synthesis of a series of uranyl compounds via oxidation of [Li(THF)4][UX5(THF)] (X = Cl, Br, I) in the presence of Ph3P=O is described. The solid state structures of [Li(O=PPh3)(MeCN)2]2[UO2Cl4], [UO2Br2(O=PPh3)2] and [Li(O=PPh3)4][I3], formed as a by-product from the oxidation of [Li(THF)4][UI5(THF)], is reported. The electronic absorption spectra and photoluminescence spectra of [UO2X2(O=PPh3)2] (X = Cl, Br, I) have been measured and no significant changes in the position of the emission (515-530 nm) or the lifetimes (ca. 1 μs) are observed in this series. However a bathochromic shift is observed in the U-X LMCT band in the electronic absorption spectrum.